Bacterial flora of the bowel has recently gained importance from a therapeutic point of view. It is now realized that the human flora, rather than just being waste material resulting from digestion of food, is an important virtual organ containing large numbers of living microorganisms. There are in excess of one hundred thousand different subspecies—or more—arranged in families and subgroups of genetically different but often linearly related organisms. The waste “material” makes up a proportion of the flora. The bacterial content of the flora is actively breaking down or metabolizing the non-absorbed matter, largely fiber, on which the bacterial cells grow. Because the bacterial flora is contained within the human body and is made up of living components it constitutes in fact as a living organ or a virtual organ.
This virtual organ can be healthy in that it doesn't contain any pathogenic organisms, or it can become infected or infested with parasite, bacteria or viruses. When infected with some pathogenic species, such infecting species can manufacture molecules that affect secretion, which can cause pain, or can paralyze the bowel causing constipation. Infection of the bowel flora or bowel flora organ can impact the health of the individual.
Many of these infections can be acute, such as cholera, but some can be chronic and can really impact on the life of the individual carrying the infected flora. For example, after antibiotic therapy some of the families of the bacteria can be suppressed or eradicated and infectious agents such as Clostridium difficile and other pathogens can lodge and become passengers within the human flora. These ‘passengers’ are also pathogenic because they can produce toxins e.g. toxins A and B for C. difficile. 